The Impacts of Land-use/cover Change on Loktak Lake Water Quality in North-Eastern Region,India

Abstract

The present study was designed to understand the long-term impacts of land-use/cover change on hydrology and nutrient dynamics of Loktak Lake in Manipur. The major land-use/cover changes are the expansion of built-up land, open forest land, aqua ponds/water bodies and wetland. There was increase in built-up land by 0.80%, open forest by 9.39% and water bodies by 1.31%. The surface inflow from rivers/streams accounts 52% of the total inflow into the lake. The annual average sediment input into the lake was estimated as 650,000 metric tonnes. The nutrient (DO, free CO $_2$ , chloride, TDS, BOD and phosphate phosphorous, etc.) levels of the lake varied between seasons and sites. High intensity of fertilizer usage in the agricultural fields and practice of fish farming contribute significantly to water quality deterioration in the lake. The highly polluted rivers (Nambul and Nambol) also finally discharge pollutants in the lake. Today, Loktak Lake has been placed on the informal list of threatened Ramsar sites of the world. Only a concerted effort on the part of official agencies, professionals, NGOs and the local communities to comprehend the complexities of this delicately balanced, biologically rich wetland ecosystem, and take appropriate action, can save Loktak Lake from demise.